This invention relates tp water distribution for irrigation purposes and, more particularly, to a water distribution plate for a rotatable sprinkler head.
Sprinkler heads of the type disclosed in U.S. Pat. No. 4,660,766 include a sprinkler body or housing having an inlet which is adapted to be connected to a source of water under pressure. The outlet is defined by a nozzle that directs the water under pressure communicating with the sprinkler body as a primary stream into the atmosphere along a generally vertically extending axis. A rotary water distribution plate (also referred to as a “rotor plate”) is provided for receiving the primary stream and directing it outwardly in a circular distribution pattern. A viscous damper mechanism is provided for reducing the rotational speed of the distribution plate from a relatively high whirling speed that would occur without the viscous damper, to a relatively slow speed.
One advantage of this type of sprinkler is that by limiting the rotational speed of the rotor plate, the water contacting the rotor plate can be projected outwardly so that stream integrity is maintained beyond the plate. Thus, the water distribution pattern can be made to closely simulate the highly desirable water distribution pattern of an impact sprinkler head.
Rotor plates are known that simply redirect the vertical stream to a substantially horizontal stream, or that first divide the primary stream into two or more streams through the use of grooves or channels radiating from the center of the rotor plate.
Rotation of the rotor plate is achieved by curving the one or more water distribution grooves or channels toward the exit ends of the grooves or channels, or by offsetting the grooves or channels from the center of rotation of the plate. Thus, water exiting the grooves causes the plate to rotate in a well understood manner. An example of a multi-channel rotor plate configuration is shown in commonly owned U.S. Pat. No. 4,796,811.
A disadvantage of the prior designs is that the radial distribution pattern has a smaller throw radius than if the grooves were straight and on center. Another disadvantage is the difficulty in maintaining a generally consistent rotation speed over a flowrate and pressure range. It is also a continuing objective to achieve good uniformity of the wetted area for all nozzle sizes, and at the same time, to increase the radius of throw so that the number of sprinklers required for a given area can be reduced.